The figure is up 8.4% and $400 billion in value from the 30,900 aircraft forecast in 2010, and up $1.4 trillion in the past five years.

Single-aisle aircraft, the largest segment in volume and value, rose by more than 10% year-over-year in Boeing's 2011 Current Market Outlook. It predicts that 23,370 100- to 210-seat aircraft, worth $1.95 trillion, will be required, up from 2010's forecast for 21,160 aircraft worth $1.68 trillion.

The increase in the estimated need for narrowbody aircraft comes one day after the airframer announced plans to further increase 737 output to 42 aircraft a month in the first half of 2014.

Of the 33,500 aircraft, 60% will be for worldwide growth, while 40% will be for replacement, creating a total fleet of 39,530 aircraft, including 6,030 retained aircraft. Today's fleet stands at 19,410 aircraft, said Boeing.

Boeing expects global GDP to grow at a rate of 3.3% year-over-year and the number of airline passengers to rise by 4.1% with heavy growth in Asia, shrinking the revenue passenger kilometre share of traffic from Europe and North America from 54% in 2010 to 39% in 2030.

Revenue passenger kilometres are expected to rise 5.1% annually, with the cargo market forecast to rise by 5.6% a year.

The second largest segment, 787 and 777 twin-aisle-sized aircraft, has increased to 7,330 aircraft, or 22% of the market by units, worth $1.77 trillion or 43% of the $4 trillion total, up from 7,100 in 2010.

Additionally, Boeing revised upward its large aircraft market estimate to 820, an increase of 100 aircraft over the previous year, reversing a downward trend in the demand for Airbus A380- and 747-8-sized aircraft.

Further, Boeing raised its regional aircraft forecast from 2010 to 1,980 from 1,920 units, representing 2% of the total value over 20 years.